Cortical regions involved in the observation of bimanual actions

Correlation of neuropsychological indicators of child development with speech: Empirical research underpinning the national children’s health prevention programme

Introduction/Aim Psychophysiological disorders and speech pathology is one of the priority public health problems in the Republic of Serbia. Child?s growth and development proceed in a particular sequence and course, depending on individual physiological capacities, quality of neuromuscular structures and stimuli, which can be significantly affected by the environment. The development of speech from birth to the adult age is a result of the interaction of neurocognitive factors that contribute to a gradual attainment of phonological presentation and motor control abilities. The aim of the study was to examine the connection between manipulative manual dexterity, oral practice and lateralization with the development and speech in children and their potential for the development of prevention programs. Methods: The sample included 60 children from Belgrade of both sexes, aged between 5.5 and 7 years. Of these, 30 made up the experimental group - children with deviations in speech development (articulation disorders), and 30 the control group - typically developing children from the general population. The instruments used were the Manipulative Manual Dexterity Test (Lafayette), Oral Praxis Test, and part of the Test for assessing lateralisation (auditory, visual, and functional). Results The hand grip development level is statistically significantly different between the experimental and the control group (??=21.40, df=3, p<0.01). The presence of associated involuntary movements statistically significantly differs between the experimental and the control group examinees (??=10.58, df=1, p<0.01). Oral praxis statistically significantly differs between the experimental and the control group (t=2,01, p<0,05). Visual laterality statistically significantly differs (??=7.56, p<0.05) between the observed groups. When all predictors are taken into account, significant contribution to the explanation of the existence of speech pathology (articulation disorders) is given by the variables: Visual lateralization (OR = 0.38; 95% CI = 0.179-0.832; p = 0.015) and the level of hand grip development (OR = 0.23; 95% CI = 0.082-0.699; p = 0.009). Conclusion: The hand grip development level and visual laterality are worse in children with speech (articulation) impairment and developmental deviations. It is these indicators of child development that should be used as a guide in designing the National programmes for developmental assessment and prevention in the child healthcare system.

Impact of Handedness Consistency on Bimanual and Unimanual Continuous Movements

Bimanual coordination is an essential human function requiring efficient interhemispheric communication to produce coordinated movements. Previous research suggests a "bimanual advantage" phenomenon, where completing synchronized bimanual tasks results in less variability than unimanual tasks. Additionally, of hand dominance has been shown to influence coordinated performance. The present study examined the bimanual advantage in individuals with consistent and inconsistent handedness. It was predicted that participants with consistent handedness would not display a bimanual advantage unlike those with inconsistent handedness. Fifty-six young adults completed a finger-tapping paradigm in five conditions: unimanual tapping with either left or right hand, in-phase bimanual tapping, and out-of phase bimanual tapping led by either left or right hand. Results were not consistent with the hypothesis that participants with consistent handedness displayed the "bimanual advantage". However, the "bimanual advantage" was not evident for the inconsistent handers when the temporal consistency was measured with either the left or right hand only. Overall, the "bimanual advantage" may be dependent upon consistency of hand preference, as well as the direction of hand dominance.

Hands in motion: an upper-limb-selective area in the occipitotemporal cortex shows sensitivity to viewed hand kinematics

Regions in the occipitotemporal cortex (OTC) show clear selectivity to static images of human body parts, and upper limbs in particular, with respect to other object categories. Such selectivity was previously attributed to shape aspects, which presumably vary across categories. Alternatively, it has been proposed that functional selectivity for upper limbs is driven by processing of their distinctive motion features. In the present study we show that selectivity to static upper-limb images and motion processing go hand in hand. Using resting-state and task-based functional MRI, we demonstrate that OTC voxels showing greater preference to static images of arms and hands also show stronger functional connectivity with motion coding regions within the human middle temporal complex (hMT+), but not with shape-selective midtier areas, such as hV4 or LO-1, suggesting a tight link between upper-limb selectivity and motion processing. To test this directly, we created a set of natural arm-movement videos where kinematic patterns were parametrically manipulated, while keeping shape information constant. Using multivariate pattern analysis, we show that the degree of (dis)similarity in arm-velocity profiles across the video set predicts, to a significant extent, the degree of (dis)similarity in multivoxel activation patterns in both upper-limb-selective OTC regions and the hMT+. Together, these results suggest that the functional specificity of upper-limb-selective regions may be partially determined by their involvement in the processing of upper-limb dynamics. We propose that the selectivity to static upper-limb images in the OTC may be a result of experience-dependent association between shape elements, which characterize upper limbs, and upper-limb-specific motion patterns.

Neural coupling of cooperative hand movements: a reflex and fMRI study

The neural control of "cooperative" hand movements reflecting "opening a bottle" was explored in human subjects by electromyographic (EMG) and functional magnetic resonance imaging (fMRI) recordings. EMG responses to unilateral nonnoxious ulnar nerve stimulation were analyzed in the forearm muscles of both sides during dynamic movements against a torque applied by the right hand to a device which was compensated for by the left hand. For control, stimuli were applied while task was performed in a static/isometric mode and during bilateral synchronous pro-/supination movements. During the dynamic cooperative task, EMG responses to stimulations appeared in the right extensor and left flexor muscles, regardless of which side was stimulated. Under the control conditions, responses appeared only on the stimulated side. fMRI recordings showed a bilateral extra-activation and functional coupling of the secondary somatosensory cortex (S2) during the dynamic cooperative, but not during the control, tasks. This activation might reflect processing of shared cutaneous input during the cooperative task. Correspondingly, it is assumed that stimulation-induced unilateral volleys are processed in S2, leading to a release of EMG responses to both forearms. This indicates a task-specific neural coupling during cooperative hand movements, which has consequences for the rehabilitation of hand function in poststroke patients.

Seeing or moving in parallel: the premotor cortex does both during bimanual coordination, while the cerebellum monitors the behavioral instability of symmetric movements

The underlying neural mechanisms of a perceptual bias for in-phase bimanual coordination movements are not well understood. In the present study, we measured brain activity with functional magnetic resonance imaging in healthy subjects during a task, where subjects performed bimanual index finger adduction-abduction movements symmetrically or in parallel with real-time congruent or incongruent visual feedback of the movements. One network, consisting of bilateral superior and middle frontal gyrus and supplementary motor area (SMA), was more active when subjects performed parallel movements, whereas a different network, involving bilateral dorsal premotor cortex (PMd), primary motor cortex, and SMA, was more active when subjects viewed parallel movements while performing either symmetrical or parallel movements. Correlations between behavioral instability and brain activity were present in right lateral cerebellum during the symmetric movements. These findings suggest the presence of different error-monitoring mechanisms for symmetric and parallel movements. The results indicate that separate areas within PMd and SMA are responsible for both perception and performance of ongoing movements and that the cerebellum supports symmetric movements by monitoring deviations from the stable coordination pattern.